During the production of many nonwoven materials, the materials are subjected to an embossing process. Embossing is a process of creating a 3-dimensional image or design into the sheet material. In one embodiment, a sheet material can be embossed by feeding the sheet material into a nip formed between an embossing roller and a backing roller. The embossing roller, for instance, may define a plurality of raised elements that form embossments into the sheet material. The embossments can be formed into the sheet material using pressure alone or in combination with heat.
Nonwoven materials that are typically subjected to embossing processes include various different tissue products, such as paper towels, napkins, bath tissue, facial tissue, premoistened wipes, and other products. The nonwoven materials can be embossed for many different reasons. For instance, embossing can be used in order to increase the bulk of the product, to improve the liquid absorption properties of the product, to increase the softness of the product or simply to improve the aesthetics of the product. Embossing can also be used to attach two or more plies of the nonwoven material together.
Regardless of the particular application, most embossing patterns are intended to improve the visual appeal of the product to consumers. Embossing patterns incorporated into tissue products and other similar materials, however, are not always completely visually perceivable. Much detail incorporated into such embossing patterns remains unnoticed.
For instance, graduated line weights are commonly used in decorative and geometric patterns to indicate flexibility, motion, perspective, and the like. Varying line weight generally means varying the thickness of a line in order to emphasize or de-emphasize different parts of the image. Varying the line weight in an embossed pattern by increasing or decreasing the thickness of the embossment, however, is not easily perceivable and thus has little effect on the overall aesthetic appeal of the pattern or design.
In view of the above, a need currently exists for a technique or method for creating a perceived line weight variation in an embossing pattern applied to a sheet material, such as a tissue product. Creating perceived line weight variations in patterns embossed into a nonwoven material can enhance the consumer appeal of the embossed product.